keith



No Model.)

' N. S. KEITH. Electric Lamp.

IIIJII'T 11 W1 names www UNITED STATES PATENT OFFICE.

NATHANIEL S. KEITH, OF NElV YORK, N. Y., ASSIGNOR TO THE FULLERELECTRICAL COMPANY, OF SAME PLACE.

ELECTRIC LAMP.

SPECIFICATION forming part of Letters Patent No. 242,137, dated May 31,1881.

(No model.)

To all whom ct may concern:

Be it known that I, NATHANIEL SHEPARD KEITH, of the city, county, andState of New York, have invented a new and useful linprovement inElectric Lamps; and I do hereby declare that the following; is a fulland exact description of the same, reference being made to theaccompanying drawing.

My invention relates to that class of electric lamps which use thevolta-ic arc, and is more especially valuable as an addition to themwhen they are used in multiple arc '27. 0., when the current from agenerator is divided among derived circuits in which are placed two ormore lamps.

Heretofore the difficulty to beovercome in dividing an electric currentbetween lamps placed in multiple are was that due to the extreme unequalresistances of the several lamps, the current, in obedience to thewcll'known laws, being divided in like unequal proportions between thelamps. These conditions have made the division of electricity betweenlamps of the voltaic-arc type impracticable. The remedy for theseconditions is the application of a device which will automaticallyadjust and keep, at least approximately, the resistances of the severallamps of definite values.

In working lamps, ordinarily, when the carbons touch each other theresistances are the lowest, and when they are separated to the allowableextent the resistances are highest. It has been found practicallyimpossible to cause the absolutely simultaneous movement of the carbonsto and fro, so as to keep the resistances of the several lamps in nearlyconstant relation. My invention accomplishes the desideratum.

Referring to the accompanying drawing, A is a helix of insulated wire,having a resistance about equal to the normal resistance of the voltaicare of the lamp to which it is attached or with which it is associated.It may be placed in any convenient place about the lamp or in itsneighborhood.

B represents several wires, which are electrically attached to places onthe wire of the helix, which places represent several equal divisions ofthe wire.

The wire 1) represents one end of the helixwire, and the wire (trepresents the other end, connected with the last strip, g.

C represents a form of insulating material, to which are attached or inwhich are embedded a series of parallel metallic strips, as many innumber as there are loops B from the resistance-coil. To these stripsare connected, scriatim, the wires B.

D is a piece of metal, of curved form on the under side, or the sidewhich rocks on the form C.

E is a wire electrically connected with one of the binding-posts at thetop of the lamp, (marked F)the negative onein this caseand with therocker D. The binding-post F is insulated from the frame of the lamp.The other binding-post for the outside circuit is in electricalconnection with the frame of the lamp and the upper carbon-holder, aftera wellknown manner, so that the current entering at said post will passto the upper or positive carbon, thence to the lower carbon.

G is a wire electrically connecting the plate g with one end of the coilof the electro-magnot H, which is a part of a lamp in use in the art.The other terminal of the eleetro-magnet is in electrical connectionwith the lower carbon-holder, which is insulated from the main frame ofthe lamp in any suitable way.

I represents an armature, which is attached to the free end of aswinging lever, havingits fulcrum at the other end, and carries theclockwork which controls the movements of the working parts of the lamp.One of the wheels of this clock-work gears with a rack upon thecarbon-carrier. The clock-work is locked and released by means of astationary yielding detent, which is engaged and disengaged with a wheel0! the train by the movements of the armature-lever carrying said train.The construction andoperation ofthcse devices are well known in the art,and need not be further described.

Other devices may obviously be used in place of those referred to forseparating the carbons and controlling the length of arc.

K is a rod which connects the swinging lever with the rocker D, so thatwhen the lever swings the rocker is rocked upon form 1) and makeselectrical connection successively with the strips and through thecorresponding portions of the helix A.

L is the rod which carries the positive electrode in this case.

The operation of the arrangement is as follows: The armature I restingatits lowest point, the rocker I) rests on the first strip 0, and thecarbons are in contact. The path of the current is then (entering at thepost in connection with the upper carboncarrier) through the uppercarbon to the lower carbon, electromagnet H, wire G, strip g, coil A,strip a, rocker D, and to binding-post F. The resistance is that of thelamp and carbons plus that of the helix A, which together is equal tothat of lamp and carbons plus that of the voltaic are due to the lamp.On making the circuit the armature I is raised by the attraction of themagnet H, and it lifts the carbon-carrier L, separates the carbons,forms the voltaic are, and also rocks the rocker D onto the severalstrips successively, thus throwing out of circuit in regular progressionthe several divis ions of the coil of the helix until the rocker rests011 the strip y, where the helix is completely out of circuit.

I do not limit myinvention to the apparatus shown, nor to thecombination with the lamp shown, as it is evident that after thisspecification other progressively varying resistance apparatus may beapplied, as well as other lamps used.

It is plain that this operation compensates for increments of resistanceat that portion of the circuit called the voltaic are by decrements ofresistance at another portion of the circuit-namely, the helix A. Asthis apparatus, then, has nearly constant resistance at all times, itbecomes possible .to place several of them in multiple are for practicalelectric ligh ting.

Having described my invention and its operation, I hereby claim 1. Thecombination, with the lifting electromagnet of an electric lamp, of aresistancecoil, loops or connections therefrom at various points, and acircuit-closer operated by said electro-magnet, the whole so arrangedthat as the carbons are separated the divisions of the resistance-coilare successively cut out of circuit.

2. The combination, with the lifting electromagnet of an electric lampwhich serves to separate the carbons to a regulated distance, oi:- aresistance-coil in the principal or direct circuit with saidelectro-magnet and a circuit closer which determines thenumber of coilsin circuit, all so arranged that as the carbons are separated by theattraction ot'said electro-magnet the total resistance of the coildiminishes.

3. The combination, with the armature of an electro-magnct whichcontrols the length of arc in an electric lamp, of an artificialresistance, loops or wires leading therefrom at grad uated points insaid resistance, and a rocking circuit-closer connected to the armature,the whole so arranged that as the armature is attracted the rockingcircuit-closer makes successive contact with the loops of said resistance, so as to cut the divisions thereof successively out of circuit.

i. In combination with the regulating electro-magnet of an electric lampwhich serves to control the length of are, a resistance at another pointin the same principal circuit with the are, and circuit-closing devicescontrolled by said regulating elcctromagnct, the whole so arranged thatthe regulating electro-magnet operates the circuit-closer and diminishesthe resistance simultaneously with its operation in increasing thelength of-arc, substantially as and for the purpose described.

5. The combination, with theregulating electro-magnet of an electriclamp, of the resistance-helix A, wires B, form C, and rockingcircuit-closer 1), operated by said electro-niagnet.

6. The combination of thelil'ting or separating electro-magnet 01' anelectric'lamp with the rocker D and link K, substantially as described.

N. S. KEITH.

Witnesses:

HERMAN L. 1%. Emma, Go. H. HINNAU.

